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The Mole

The Mole. Unit 7: Stoichiometry – Part I Mrs. Callender. Lesson Essential Questions. What is a mole? What is a mole used for?. Atoms are really, really small……. We can not work with individual atoms or AMU’s in the lab. Atomic Mass Unit. WHY?. Because we can’t see things that small!.

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The Mole

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  1. The Mole Unit 7: Stoichiometry – Part I Mrs. Callender

  2. Lesson Essential Questions What is a mole? What is a mole used for?

  3. Atoms are really, really small…… We can not work with individual atoms or AMU’s in the lab. Atomic Mass Unit WHY? Because we can’t see things that small!

  4. We as scientists work with portions of matter large enough for us to SEEand MASS on a balance using units of…… gramS

  5. This presents a problem….. A pile of atoms large enough for us to see contains billions of atoms. So how would we keep track of that many atoms? Copper (II) Sulfate

  6. Chemists came up with a new unit. The MOLE

  7. Equivalents or Conversion Factors 1 dozen eggs = 12 eggs 1 ream of paper = 500 pieces of paper 1 rooster = two legs

  8. Equivalents or Conversion Factors 1 mole = 6.02 x 1023 There are EXACTLY 12 grams of Carbon-12 in 1 mole of Carbon-12.

  9. I did not discover the number. It was just named after me. Avogadro’s Number 6.02 x 1023 He studied gases and discovered that no matter what the gas, there were the same number of molecules present. Named in honor of Amadeo Avogadro. 1776 - 1856

  10. Units for Avogadro’s Number For instance: 1 mole of pennies = 6.02 x 1023 pennies. 1 mole = 6.02 x 1023 (many different units) This amount is equivalent to 7 stacks of pennies from the Earth to the moon.

  11. Units for Avogadro’s Number Remember: HOFBrINCl 1 mole Mg= 6.02 x 1023 atoms. 1 mole NaCl= 6.02 x 1023 molecules. 1 mole Cl2 = 6.02 x 1023 molecules. 1 mole SO4-2 = 6.02 x 1023 ions.

  12. Calculating Formula Mass Calculate the formula mass of NaCl. 6 Na 22.9897 17 Cl 35.453 22.99 g + 35.45 g = 58.44 g Therefore, 1 mole of NaCl (6.02 x 1023molecules) has a mass of 58.44 g

  13. Calculating Formula Mass Calculate the formula mass of K2O. 19 K 39.0983 6 O 15.9994 2(39.10) g + 16.00 g = 94.2g Therefore, 1 mole of K2O (6.02 x 1023molecules) has a mass of 94.2g

  14. Calculating Formula Mass Calculate the formula mass of (NH4)2SO4. 7 N 14.0067 1 H 1.00794 16 S 32.066 6 O 15.9994 2(14.01) g + 8(1.01) g + (32.01) + 4(16.00) g = 132.11 g Therefore, 1 mole of (NH4)2SO4 (6.02 x 1023molecules) has a mass of 132.11 g

  15. Calculating Formula Mass . Calculate the formula mass of CuSO45 H2O. This type of formula is called a hydrate. It is a salt with water physically attached to it. 29 Cu 63.546 16 S 32.066 6 O 15.9994 1 H 1.00794 Example: A salt container with rice intermixed. Since the water is physically attached how could it be removed? . 63.55 g + 32.01g + 4(16.00) g + 5[2(1.01)+16.00] =249.56 g Therefore, 1 mole of CuSO4 5 H2O (6.02 x 1023molecules) has a mass of 249.56 g By heating. When the water is removed the remaining salt is called anhydrous.

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